Stiffening material for shoe parts

ABSTRACT

THIS INVENTION PROVIDES A STIFFENING MATERIAL FOR SHOE PARTS COMPRISING A NON-WOVEN FABRIC IMPREGNATED WITH A RESIN. THE FABRIC COMPRISING A SELF-SUSTAINING BATT OF MONWOVEN FIBERS EXTENDING GENERALLY IN THE WIDTHWISE DIRECTION OF THE FABRIC AND A PLURALITY OF ROWS OF YARN STITCHES EXTENDING GENERALLY IN THE LENGTHWISE DIRECTION OF THE FABRIC. THE ROWS ARE SPACED APART A DISTANCE LESS THAN THE AVERAGE LENGTH OF SAID FIBERS.

Aug. 13, 1974 A. w. CLOSSON ETAL 3,829,351

STIFFENING MATERIAL FOR SHOE PARTS Filed Sept. 28, 1972 United StatesPatent Office Patented Aug. 13, 1974 3,829,351 STIFFENING MATERIAL FORSHOE PARTS Addison W. Closson, Cambridge, and Harry L. Beckwith, Dedham,Mass., assignors to Beckwith Corporation, Wakefield, Mass.

Filed Sept. 28, 1972, Ser. No. 293,078 Int. Cl. A43c 13/14; D/04h 5/02US. Cl. 16150 12 Claims ABSTRACT OF THE DISCLOSURE This inventionrelates to a new stiffening material useful for forming shoe parts,particularly box toes and counters and to a method for making the same.

Prior to the present invention, box toe and counter stiffeners have beenmade by impregnating a woven or felted fabric or a needled fabric with aresin composition and thereafter fusing the resin. While these fabricshave been satisfactory for use in box toe and counters, their strengthcharacteristics have not always been satisfactory, particularly alongthe bias, and their ability to distribute impact load is undesirablylimited. In addition, these materials are relatively uncompressed andthick and they tend to show up when incorporated in the shoe because oftheir bulk. Relatively thick stiffening materials also are undesirablein the resin fusing step. The thermal conductivity of the material isreduced because of the increased thickness thereby requiring eitherhigher curing temperatures or increased residence time during heating.When solvent fusion is employed, thicker materials absorb greateramounts of solvent which must be removed subsequently. Attempts toreduce the thickness of these materials have not been successful sincethe strength characteristics of the resultant material is undesirablyreduced. In addition, the concentration of resin needed to form thefinal material is relatively high and therefore costly.

It has been common practice to impregnate a flannel fabric with a resinlatex which is fused subsequently to form a stiffening material for shoeparts. While this material is satisfactory in some applications, veryoften it is undesirably brittle. The undesirable brittlenesscharacteristics of this stiffening material arise since the fiberconcentration at the surfaces of the stiffening material is too low toprovide flexibility to the resin. In addition, in cotton flannel thefiber density within the interior of the flannel is too high to absorbsufficient resin to provide the desirable strength characteristics ofthe resultant stiffening material. The same brittleness problem arisesfrom the use of fabric formed by needling rayon or nylon fibers into ascrim since these needled fabrics tend to pick up a high concentrationof resin as high as 80% by weight of the final product. Attempts toincrease the density of the fibers in the needled fabric to reduce theconcentration of resin in the final product have not been completelysuccessful and the resultant stiffening material is too thick and loftyfor the most satisfactory use for shoe toes.

When employing resin-impregnated, double napped, cotton flannel sheets,counters must be cut across the sheet from selvage to selvage to obtainthe stretch necessary to avoid counter wrinkling or breakage. This typeof cut is used also to attain maximum hardness since the warp fibersextend vertically in the counter placed in the shoe and have no stretchthereby reinforcing it. This cutting requirement results in a relativelylarge portion of the sheet being wasted.

The stiffening material of this invention comprises a non-woven fabricimpregnated with a resin which fabric comprises a self-sustaining battof carded non-woven fibers such as rayon or nylon extending generally inthe widthwise direction and a plurality of rows of yarn stitchesextending generally in the lengthwise direction of the fabric. Thenon-woven fiber need not extend in a direction parallel to the widthwisedirection but can be slightly angled from the width-wise direction up toabout 45. The fibers employed have an average length generally betweenabout /2 and 4 inches and the rows of yarn stitches are spaced apart adistance less than the average length of the fibers, generally between/a and of an inch.

The stiffening material of this invention provides substantialadvantages over those of the prior art. The outstanding and surprisingadvantage of the material in this invention is that it exhibits greatertensile strength along the bias as compared to the warp or fill tensilestrength. Since impact for a box toe is regulated primarily by thedistribution of the impact force throughout the area surrounding thepoint of impact, the higher strength against rupture on the bias isexceedingly important. This observation is in direct contrast with thestiffening materials of the prior art wherein the maximum tensilestrength is in the warp and fill direction and the tensile strengthalong the bias is some intermediate value, usually the average of thewarp and fill tensile strength.

The stiffening material of this invention also is far less brittle thanthose of the prior art thereby permitting the use of more severeconditions during a molding step during which the material isincorporated in a shoe construction. The stiffening materials of thisinvention also has a thinner gauge than those of the prior art andtherefore will show through a leather upper to a lesser degree, which insome cases eliminates the need for skiving. The reduced thickness alsopermits the use of less severe conditions during heat curing and reducessolvent pick-up during solvent fusion. 1

Furthermore, the resin-impregnated sheet material of this invention canbe cut in any direction to form shoe parts having satisfactory stretchand strength characteristics. Thus counters and liners cut from thissheet material, regardless of the orientation of the cut, havesufficient stretch to avoid wrinkling or breakage under normal impactforces and have excellent hardness characteristics even when cut on thebias. These characteristics permit cutting the sheet material whileminimizing waste material.

The fabric of this invention can be formed from a wide variety of fibersincluding rayon, polyamides (nylon), polyester, cellulose, wool, blendsthereof or the like. When it is desired to increase the flexibility andresilience of the stiffening material, it is preferred to employ afabric formed from a polyamide. When it is desired to improve thestiffness and strength characteristics of the stiffening material, it ispreferred to employ a fabric formed from rayon fibers.

Suitable resin latexes include styrene, styrene copolymers, such asstyrene-acrylates, styrene-butadiene, and styrene-acrylonitrile orpolyvinylchloride or polyvinyl acetate, natural rubber and low molecularweight styrene impregnated as a hot melt or the like. In the finalstiffening material, the resin comprises between about 50 and weightpercent based upon the weight of impregnated fabric. The finalstiffening material generally has a thickness between about .030 and.090 inch, and can be controlled by varying the density of the fibers inthe base fabric.

The strength characteristics of the stiffening material also can bevaried by varying the distance between the rows of stitched thread, thestrength of the yarn employed in the stitching and the density of thestitch. Higher' strength characteristics are obtained by reducing thedistance between the stitch rows, increasing stitch density or employingstronger yarns. There is no limit as regard to the type of stitch withzig zag, chain stitching, or lock stitching being satisfactory. Inaddition, stitching beween the rows can be provided such as exampleshown in U.S. Pat. 3,329,552 issued July 4, 1967. This patent alsodiscloses one method for laying the fibers in a widthwise direction.

The method for forming the stiffening material of this inventioncomprises impregnating the fabric with a resin latex, drying theimpregnated fabric and curing or fusing the resin therein by heating orsolvent fusion. The method of this invention will be more fullydescribed with reference to the accompanying drawings.

FIG. 1 is a schematic view of the process steps of this invention.

FIG. 2 is a plan view of a box toe of this invention.

FIG. 3 is a cross sectional view of the box toe taken along lines 33 ofFIG. 2.

Referring to FIG. 1, the fabric 1 is advanced into a bath of resin latex2, over guide roller 3 and beneath the surface of the bath 2 under guideroller 4 so that the base fabric 1 is saturated with the resin latex.After leaving bath 2, the impregnated fabric 5 is passed between squeezerollers 6 and 7 to remove excess latex on resin therein. The saturatedfabric 5 then is passed over heated or cooled drums 8 and 9 and throughsqueeze rollers 10 and 11 to obtain an impregnated fabric 12 having thedesired thickness. Thereafter, the resin can be fused or curedconventionally such as by heating or by being contacted with a solventwhich fuses the resin.

Referring to FIGS. 2 and 3, the stiffening material comprises a basefabric formed from a batt of non-woven fibers 15 which extends generallyin the widthwise direction of the fabric and a plurality of rows of yarnstitches 16 which extend generally in the lengthwise direction of thefabric and, as shown in FIG. 3, can comprise a stitch-loopconfiguration. As shown, the box toe 17 is cut at an angle to itsthickness along the base 18 thereof to promote fitting of the box toe ina shoe.

The following examples illustrate the present invention and are notintended to limit the same.

EXAMPLE I This example illustrates a method for forming the stiffeningmaterial of the invention and the superior strength characteristics ofthis material as compared with stiffening material made with a needledbase fabric or a cotton flannel fabric. A stitch-bonded base fabriccomprising rayon fibers extending generally in the widthwise directionand stitched rows of a polyester yarn extending in the lengthwisedirection of the fabric was impregnated with a styrene acrylate latex,dried at 120 C. for about 8 minutes and fused by toluene immersion. Thebase fabric, prior to resin impregnation weighed 7.8 oz. per squareyard, the yarn was loop-stitched with twelve stitches per inch and therows were inches apart. The cured stif fening material contained about70 wt. percent resin and was .043 inches thick.

The same resin impregnation and curing steps were repeated with aneedled fabric comprising rayon fibers needled into a cotton scrim andwith a cotton flannel fabric. The needle fabric prior to impregnationweighed 8 oz. per square yard and the final cured stiffening materialformed therefrom was .073 to .083 inches thick. The cotton flannelweighed 8.4 oz. per square yard and the final cured stiffening materialformed therefrom was .058 to .065 inches thick. Theneedled stiffeningmaterial contained 77 weight percent resin based upon the finalstiffening material. The cotton flannel stiffening material contained 73weight percent resin based upon the final stiffening material.

Each stiffening material was tested for tensile strength and stretch atrupture on a Scott apparatus with the following results:

TABLE I Stitch bonded abric Needled fabric Flannel Tensile StretchTensile Stretch Tensile Stretch (lbs.) (in.) (lbs.) (in.) (lbs.) (in.)

The procedure of Example I for forming stiffening materials from a basefabric and a resin composition was repeated With a double nap cottonflannel fabric weighing 6 /2 oz. per square yard, a wide stitch bondedfabric formed from rayon fibers with stitch rows spaced /8" apart andweighing 7 /2 oz. per square yard, and a narrow stitch-bonded fabricformed from rayon fibers with stitch rows spaced apart A" and weighing 5/2 oz. per square yard. The cured resin-wide stitch bonded materialcontained 77 weight percent resin. The cured resin-flannel material was.036 inches thick and contained 73 Wt. percent resin. The curedresin-narrow stitch-bonded material was .038 inches thick and contained70 weight percent resin. Each material was tested as described inExample I with the following results:

TABLE II Wide stitch- Narrow stitch- Napped flannel bonded bondedTensile Stretch Tensile Stretch Tensile Stretch (lbs.) (in.) (lbs.)(in.) (lbs.) (in.)

28 16 1 ,18 28 48 2% a l 2% 17 2% a 34 17 20 2% 53 2% As shown in theabove table, only the stitch bonded material of this invention had ahigher tensile strength on the bias as compared to the warp or filltensile strength.

We claim:

1. A stiffening material for shoe parts comprising a non-woven fabricimpregnated with a resin, said fabric comprising a self-sustaining battof non-Woven fibers extending generally in the widthwise direction ofsaid fabric and a plurality of rows of yarn stitches extending generallyin the lengthwise direction of said fabric, said rows being spaced aparta distance less than the average length of said fibers.

2. A stiffening material for shoe parts comprising a non-woven fabricimpregnated with a resin latex, said fabric comprising a self-sustainingbatt of non-woven fibers extending generally in the widthwise directionof said fabric and a plurality of rows of yarn stitches extendinggenerally in the lengthwise direction of said fabric, said rows beingspaced apart a distance less than the average length of said fibers.fib3. The material of claim I wherein the fibers are rayon ers.

4. The material of claim 2 wherein the fibers are rayon fibers.

5. The material of claim 1 wherein the fibers are polyamide fibers.

6. The material of claim 2 wherein the fibers are polyamide fibers.

7. The material of claim 1 wherein the fibers are polyester fibers.

8. The material of claim 2 wherein the fibers are polyester fibers.

9. The material of claim 1 wherein the fibers are cellulose fibers.

10. The material of claim 2 wherein the fibers are cellulose fibers.

11. The material of claim 1 wherein the fibers are wool fibers.

12. The material of claim 2 wherein the fibers are wool fibers.

6 References Cited UNITED STATES PATENTS 3,336,183 8/1967 Larner, 11.,et a1. 161-Di' g. 2 3,329,552 7/1967 Hughes 161-52 2,676,128 4/1954Piccard 161--Dig. 2 2,723,935 11/1955 Rodman 16l-Dig. 2 2,498,077 2/1950Goldberg 28-77 X 3,329,116 7/1967 Attwood et a] 28-77 UX 2,125,7988/1938 McMurray 3677R FOREIGN PATENTS 1,147,657 4/1969 Great Britain16150 PHILIP DIER, Primary Examiner U.S. c1. X.R.

2877; 36-77; 161--Dig. 2

